The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingIntegration relay
On-vehicle inspection
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Inspect integration relay
Notice:
The efi relay ...
Fastening the seat belt (for the rear center seat)
Press the plate to release, and
then pull the seat belt.
Push the plate into the buckle in
the order of plate “a” and plate
“b” until a clicking sound is
heard.
Plate “a”, buckle “a”
Plate “b”, buckle “b”
...
Oxygen sensor circuit
Description
In order to obtain a high purification rate of the carbon monoxide (co),
hydrocarbon (hc) and nitrogen
oxide (nox) components in the exhaust gas, a twc is used. For the most efficient
use of the twc, the
air-fuel ratio must be precisely controlled so that it is always close to ...